The invention relates to steam turbines and, more particularly, to cooling a tub region of a double-flow steam turbine.
Double-flow steam turbines typically include two parallel flow turbine ends arranged on a common shaft. A tub section is often located between the turbine ends and disposed around the shaft. Steam flows into the steam turbine radially inwardly toward the tub section, and the steam flow then divides, turns axially, and flows in opposing directions to enter each of the two parallel flow turbine ends.
Steam flow may become stagnant between the rotor and the tub section of the double-flow steam turbine resulting in a high temperature on the rotor due to windage heating of the stagnant steam. That is, the area in which steam flow is stagnant may have an increased temperature as compared to the temperature in other areas of the turbine. Achieving a steady state temperature facilitates avoidance of component failure. High rotor temperature potentially shortens the useful life of the rotor and may lead to failure of the steam turbine.